When a vehicle is driven, it is desirable to keep the driver's attention as close to the road as possible. It is therefore desirable to place frequently-used vehicle controls on the steering wheel to minimize the driver's attention away from the road when adjusting the controls. Such vehicle controls are typically used to control the vehicle's headlights, horn, windshield wipers, cruise control, etc.
With the growth of computer technology, it is now common for electronically-controlled devices in a vehicle to exchange control data or status information via a data communication bus implemented in the vehicle. For heavy-duty vehicle applications, the Society of Automotive Engineers (SAE) has established a number of protocols to help standardize such data communication, e.g., SAE J1708/1587 and SAE J1939. The SAE J1939 protocol is an extended address protocol conforming with the Controller Area Network (CAN) standard that is well-known in the industry.
However, present day steering wheel controls for vehicles in the heavy truck and trailer industry are not configured to take advantage of the vehicle's data communication bus. Currently, steering wheel inputs, such as switches and controls on a truck's steering wheel assembly for controlling headlights, cruise control, windshield wipers, etc., are directly wired to relays in the vehicle that control the respective devices. Present means for wiring the steering wheel inputs to the devices in the vehicle are heavyweight, complex, and do not readily allow for future developments or modifications. Furthermore, changing the steering wheel wiring to accommodate individual preferences for the steering wheel inputs is difficult and expensive.
A need, therefore, exists for a steering wheel electronic interface that reduces the wiring required and increases the flexibility to add or modify functions and controls to the steering wheel inputs without having to redesign the truck electrical system. The present invention is directed to satisfy these needs and other shortcomings in the prior art.